Method of manufacturing the covers of pneumatic tires



T. SLOPEH. METHOD 0F MANUFACTURING THE COVERS 0F PNEUMATC TIRES.

AFPLICATION FILED FEB.12| 1920. 1,372,567,

/NVENTOR Patented Mar. 22, 1921.

PATENT OFFICE.

UNITED STATES` `THOIDIAS SLOPER, 0F DEVIZES, ENGLAND.

METHOD F MANUFACTURING THE CGVERS 0F PNEUMATIC TIRES.

Specification of Letters Patent.

Patented Mar. 22, 1921.

Application filed February 12, 1920. Serial No. 358,217.

To all whom timmy concern Be it known that I, THOMAS SEOPER, a subject of the King of England, residing at Devizes, Wiltshire, in England, have' inmatic tube, is partially vulcanized on a drum or former, the surface of which is approximately Hat in a direction parallel tb its axis.v 'A flat flexible endless band isthus obtained which is subsequently, before the final vulcanizing process, expanded into the form which it is desired that it shall have. Methods adopted heretofore for expanding the band, in which appliances, such as a mechanically expanded ring, have been used, however, have been found to produce local strains in the substance of the cover, which frequently develop into premature defects when the tire is in use.

By the term flat band as applied above, is meant a band of which the inner surface is approximately flat in cross-section, although the-'thickness of such a band is not necessarily uniform, and its outer surface,

which eventually forms the tread of the tire, may b'e ribbed or otherwise formed inthe usual manner. E

It has previously been proposed to bring these tire bands to approximately tirecover shape by mounting the flat annular Y band on a drum with a collapsed pneumatic tube disposed in a channel in the face of the drum, and then pushing the vedges of the band toward each other as the pneumatic tube is inflated. With this arrangement there is no means for preventing stretch of the edges of the tire-band except their own construction and there is no means for keeping the tire-cover in shape during vulcani-- zation unless the inflated tube remains in it, which is a costly method because the tubes .are destroyed by the repeated heating after use with a few covers.

The obj-ect of the present inventionis to pinovide an improved method of shaping the covers of pneumatic tires, whereby a fiat endless band can be expanded to the desired size without roducing local strains in the material cf t e band, and whereby the expanded band can be retained for vulcanizing purposes in its expanded condition mechanically, that is to say without the use of any pneumatic means such as an inflated tube, so that-the above mentioned drawback attaching to the use of such tubes is obviated The invention will now be described with reference to the accompanying drawings which show one form of apparatus adapted for carrying the improved method into prac-A Figure l 1s a central vertical section through the .appara us with the tire-band lin-place but not yet ubjected to fluid-pressure;v v

Fig. 2 is a section through the apparatus 'f with the parts in the position occupied when the tire band is expanded under uid-pressure and the retaining-ring has been released therein;

Fig. 3 is a plan of the retaining-ring and.'

its restraining and releasing mechanism;

Fig. 4 is an elevation of the same;

Fig. 5 is a plan of the parts shown in Fig. 3 but with the retaining-ring expanded Fig. 6 is a side elevation of part of the retaining-ring showing the arrangement of the springs therein;

Fig. 7 is a View of these-parts from within the ring.

The same letters indicate the same parts throughout the drawings.

The fiat'tire-band A is built up in the usual manner on a drum orformer, and is preferably partially vulcanized before inserting it between the plates B, B1. rlhese plates are provided with recesses B2 to receive the edges of the tire-band, and the top plate is fixed to the head of a press and the bottom plate is carried by a ram G. The outer edge B3 of each recess is shaped to provide a lip which bears against the outer face of the band at the point where the bead adjoins the main body of the band, and the recess is shaped moved angular louter overlapping end.v

l nectedl by the pivot-pin 5.

through a cock D4 with an air-reservoir D5 in which an auxiliary supply of air is stored. .The branch d2 is for blowing off only by means of a cock De'.

The bottom 1plate B1 is arran ed to be y about thel ram that is circumferentially relatively to the tlre-band A and to enable it to be so moved it is provided with a radially-projectin lever B4. Resting on the plate B1, an if desired Amade integral therewith, is a central block 'E encircled by an expansible ring F which is divided at one point.

When the parts are in the position shown in lFigfl,v the ex ansible ring is coiled around the block with its ends overla ping, as shown in Fig. 3, and is restraine from assuming its circular form by means of an approximately radial pini"1 on the end-segment which 1s innermost, which pin enters a hole in the side of the block. The outer end is restrained by a pin F 2,which is perpendicular to the plane of expansion .of the ring and engages a hole in the side of the This pin is carried by a lever F svwhich constitutes the releasing means for the rin the said lever being pivoted in the bloc at F4 and arranged so that 'its free end F3* projects above the blockC when the pin F2 thel ring. 's The ring is composed .of a number of is in positionfor engaging lchanneled segments, see Figs. 4, 6 and 7,

which are hinged end-to-end about pivotpins F5. The se .ents are disposed with their channeled sides toward the center of the ring and the side walls of each channeled segment are bent toward each other at one end as shown at F", Fig. 7, to lie between those of the adjacent segment to serve as ears whereby the two se ents can be con- The pivot-pin lies toward the inner edge of the ring and the outer edges of the segments butt against each other to limit the degree of expansion permitted. q

Springs G and G1 are disposed one at each side of each pivot-pimand within the .channels of the segments." One end of the spring G is connected to an ear-piece G2 secured to the left-hand segment shown in F 1g. 7, andthe other end of the same spring is connected'to an eariece Gs secured to the right-hand segment s kgwn in Fig. 7 The spring G1 has one end connected to an earpiece G* secured to the right-hand segment and the other end of this s ring is connected to an ear-piece G'i secure to the left-hand segment. The ear-pieces G2 and\G4 lie on theouter side of the pivot-pin F, so that the sprln tend always to brin the segments into t e position lshown in Figs. 5 and 6. When in this position the ring is fully eX- panded and t e two segments whose adjacentl ends are not `connected together, are

provided with flat butting faces so that they can butt one against the other.

The operation of this apparatus is as follows A tire-band having been placed in osition between the plates B, B1, the plate 1is advanced by the ram C toward the plate B andV at the same time air is admitted under pressure from the reservoir D5 by opening the cocks D4 and D72, and cocks and Dc being closed. Thisadmission of air tends to expand the tire-band A and also Dresses it against the lips B3 of the plates B1, to effect a proper seal therewith. As the plate B1 is advancedl toward the late B, the pressure of the air increases in t 1e chamber formed by the plates and the tire-band, so that the center of the tire-band is thrust outward, whereby the desired shaping is effected. During this operation, the expansible retaining-ring F is held in the contracted position by its restraining means, as shown in Figs. 1 and 3, but when the plate B arrives at the limit of its movement and the tire-band A is fully stretched, the free end of the releasing lever F8 comes into contact with the plate B, so that the lever is rocked about its pivot F, and the pin F2 at the other end is thereby broulght out from engagement with the ring F. he ring thus being released, immediately expands under the action of its springs to the circular form shown in Fig. 5, in which form it lls the annular space constituted by the shaped central portion of the tire-band. The ends ofthe ring then gap apart as shown at F7, but when the air-pressure is released, the tire-band contracts and causes the ends of the ring to butt one against the other, so that the rin then constitutes a rigid hooplike strut wlthin the tire-band.

After the expansible ring has been brought into osition, the cock D4 is closed and the cock 6 is opened to relieve the pressure, the plates are then"I separated, and the shaped tire-cover is removed on the ring, and with the ring still an @im can be finally vulcanized.

For tires of large cross-section, it may not be found necessary to admit air under pressure to the chamber between the plates, as the relative movement of the plates being greater than for tires of smaller cross-section as will be understood, the approach of one toward the other so rapidly raises the pressure in the chamber that a suiciently Huid-tight joint may be secured immediately and the further approach of one plate to the other raises the pressure suiiiciently to eff feet the required expansion without any initial pressure being set up before movement of the one plate toward the other commences; in fact, a relief-valve may be provided so that some air may escape to prevent undue pressure being set up.

be admitted from the reservoir D5 duringv the movement of the plate B1 as already described, and then the cock D4l may be closedl and the cock D3 opened, so that air at higher pressure is admitted to they chamber D1. After the tire-band has been shaped and the cock D3 closed, the cock D* may be opened to admit some of the air under pressure from the chamber D1 to the reservoir D5, so as to' economize in compressed air, but as soon as a balance is obtained, the cock D4 is closed and the blow-off cock Da opened.

The cock D2 is used to shut ofi' the conduit D when the reservoir DE is being charged through the cock D8.

When the tire-band is made up oflone or more layers of diagonal threads, it may be found desirable in the caseof large sizes of tireto turn one plate relatively to the other to equalize the tension on the threads, and vfor this purpose one of the plates is arranged so that it may be revolved in ,relation to the other when the lever Bt is used. It will berappreciated that as the tire-band is shaped, the angle lat which-thethreads cross from side to side of the band is slightly altered and the movement lci the plate allthe plates and the edges of the tire-band, it

- may sometimes be desired to use packingdii strips in the recesses of the plates.

It will be seen that' in the ap aratus according to this invention, the e ges of the v tire-band always have their outer faces in engagement with the edges of the grooves or recesses in the plates, so that the edges are not only held in the required position but no expansion of the same can take place even should the build of the edges be such as would allow of stretching.

'Ihe use of theretaining-ring enables the tire-bands to be vulcanized in an expanded condition without the aid of a pneumatic tube, and as the retaining rings can be used almost indefinitely, a considerable saving of cost of manufacture results as compared with apparatus wherein a pneumatic tube has to be used to keepthe tire-band in shape during vulcanization, for these tubes, as is well-known, do not last long when so used and they are expensive.

It will be appreciated may be employed for releasing the restrainingmeans of the retaining-rin and the opy eration of the same may e variously effected. As shown, the operation of the release from without the chamber is effected by the movement of the plate B1, but the lever or other releasin udevice could be operated by means exten in through a gland in one of the plates. Similarly, various forms of catches could be used for securing the two ends of the ring Finstead of the that various means I pins F1 and-F2; also the expansible ring itself can be variously constructed, all -that is required being thatk it shall be capable of bein made to occupy a smaller area than that of the tire-band before it is' expanded vand of expanding to fit the tire-band and hold it extended after it is expanded.

It will be seen that tires'shaped by the method described and which consists in expanding the central portion of the tire by the direct action of Huid-pressure and re taining it in this expanded condition for vulcanizing purposes by means of a device -which is brought into operative position within the tire-band'while the latter is in the expanded condition, have corresponding parts all around their circumference subjected to equal strain in'manufacture, as the cover, with the exception of the edges, is free while it is being shaped so that the different parts can aline themselves.

The retaining-ring may obviously be vari ously made and could 'for example take the form of a number of segmental parts moved out radially by a suitable mechanism; such devices are already well-knownas used for collapsible former's and therefore need not be described in detail. The retaining-ring in whatever form it takes may be arranged -Vto expand as the central portion of the tire expands, instead of being first restrained and then released when the band has been Jfully expanded; for example, the ring F' until it finally assumes the position'shown in Fig. 2. i

In wired-on tires, the engagement between the edges of the recessed plates and the bead need notv be depended upon to hold the edges against radial expansion as in fact the parts of the tire-band which bear against these lips may in some cases be Hat as the wires prevent undue radial expansion.

It will be understood that by the direct action of yfluid pressure in the specificationl and claims, is meant that the fluid is so applied to the interior of the cover that no separate air-container such as an inner tube is required.

The termfluid-tight jointA as used throughout the specification and claims for the joint made between the tire-band and plates, is intended to cover such a joint as is suliiciently fluid-tight for theA purpose.

tire cover, the steps of expandingfto the desired size the central portion of a flat endless tire-band around an expansible contracted non-pneumatic member under the pressure of a fluid in direct contact with the lnner surface of the band, positioning said ,expansible member to receive and retaln the expanded band in its expanded condition, releasing the Huid pressure from the inner surface of the band and thereby retaining the expanded band in its expanded condition on said member, and vulcanizing the band while itis thus mechanically retained expanded,'substantially as described.

2. In the method of making a pneumatic tire cover, thev steps of expanding the central portion of a flat, endless tire band around a contractedY expansible member `under`the pressure of a fluid in direct contact with the inner surface of the band to the desired size, said expansible member being fnormally urged by a force tending to expand it, releasing the expansible member and thereby retaining the expanded' band in its expanded condition, and vulcanizing the band While the same is thus retained 1n its expanded condition.

tion on said member 3. In the method Iof making a pneumaticl tire cover, the steps of expandmg the central portion of a flat endless tire band around a contracted ex ansible member under the pressure ofva uid in direct contact with -the inner surface of the band to the desired size, which expansible member is normally urged by a force tending to expand it, automatically releasing the expansible member after the band has been expanded and thereby retainin the expanded band in its expanded condition, and vulcanizing .the band While the same is retained in its expanded condition.

4. In the method of making a ipneumatic tire cover, the steps of retainingI and sealing the edges of the sides of a iat endless tire band surrounding an expansible conv tracted member in closure members which 'close the sides of the band and form with the band a closed chamber having a diameter equal to that of the band, increasing the viuid pressure in said chamber and thereby band While it is thus retained expanded, for the purpose specified.

5. In the method of making a pneumatic tire cover, the steps of retaining and sealing the edges of the sides of a fiat endless tire band surrounding an expansible contracted member in closure members which close the sides of the band and form with the band a closed chamber having a diam-- eter equal to that of the band, increasing the fluid pressure in said chamber by forcibly advancing one of said closure members toward the other, whereby the capacity of the chamber is reduced, and thereby expanding the central portion of the band to the desired size, positioning said expansible member to receive and retain the expanded band in its expanded condition, releasing the fluid pressure from the inner surface of the band and thereby retaining the expanded band in its expanded condition on said meinber and .vulcanizing the-band While it is thus ietiined expanded,\for the purpose speci- 6. In the method of making a pneumatic tire cover, the steps of retaining and sealing the edges of thc sides of a f flat endless tire band in closure members which close the sides of the band and form with the band a closed chamber having a diameter equal to that of the band, increasing the Huid pressure in said chamber by forcibly adl vancing one of said closure members toward the other and admitting a iuid under pressure into said chamber, and thereby expanding the central portion of the band to the desired size, mechanically retaining the expanded band in its expanded condition by pressure applied on the inner surface of the band, and vulcanizing the band While` it is thus retained expanded, for the purpose specied.v

7. In the method of making a pneumatic tire coverythe steps of expanding to the desired Size thecentral portion of a Hat endless band under the pressure of a Huid in direct lcontact with the inner surface of the band which forms'the periphery of a closed chamber whereof its side walls are rigid and one can be lforcibly advanced toward the other, automatically mechanically retaining the expanded band in its expanded condition, and vulcanizing the band `while it is thus retainedexpanded, for the purpose specified.

In testimony whereof I afiix my signature.

THOMAS sLoPER. 

